2. Contact Info

3. Dealer Selection

Mercedes will begin manufacturing its E-Class mileage-meister next year. When the company’s first diesel-electric powered car was previewed at the Geneva auto show in March 2010, production was promised for 2011. Now executives admit the hybrid version of the E-Class won’t be showroom-ready until sometime in 2012.

Not only has the launch date slipped, but so has fuel economy. According to Joachim Lindau, senior manager for E-Class (and CLS) testing, the target for the production E300 BlueTec Hybrid is 53 mpg in the standard European fuel consumption test. While impressive, this is 4 mpg less than the efficiency promised a year ago at Geneva. What hasn’t changed is the hybrid’s horsepower. Lindau says the combined maximum output of the diesel-electric powertrain remains 221 hp.

News of the production delay for the hybrid came at a recent event in Germany to preview a slew of efficiency-enhancing powertrain changes for the existing E-Class range. Notably, the gasoline-burning V-6 and V-8 used since launch in 2009 are replaced by the more powerful engines introduced late last year in the closely related CLS. This means an all-new 302-hp direct-inject 3.5-liter V6, plus a downsized 402-hp direct-injection and twin-turbo 4.7-liter V-8. The four-cylinder powertrains, not sold in the U.S. but popular almost everywhere else, were also significantly updated. And it’s here that likely reasons for the delay in the hybrid program are to be found.

The E300 BlueTec Hybrid is to be based on the E250 CDI with its 201-hp 2.1-liter four-cylinder turbodiesel. But before hybridization, a bunch of enabling technologies need to be in place. These preparations are still some way from completion. The E250 CDI gained two of those technologies in the recent round of upgrades; it now has an auto start-stop system, and Mercedes’ hybrid-friendly seven-speed auto has replaced the five-speeder. But the E250 CDI still lacks some vital technologies. The biggest of these is electric power steering, deemed essential for any hybrid.

Mercedes introduced a very fine electric power steering system last year in the CLS, and it’s now also being installed in the upgraded V-6 and V-8 engined E-Class models. But engineers say it will be months before the steering of four-cylinder E-Class models is electrified. Until that’s ready, no hybrid.

The finished diesel-electric E300’s 20-hp electric motor will be capable of solo propulsion, but only for brief periods, and only at speeds below 22 mph. (It’s believed the car will use the same small lithium-ion battery pack as the S400 gas-electric hybrid.) But the inclusion of a clutch between engine and motor allows the so-called ‘sailing’ coastdown that’s a fuel-saving feature of Porsche‘s Cayenne hybrid, and boosts the battery-recharging effect of regenerative braking.

Mercedes-Benz insists the E300 BlueTec Hybrid is intended primarily for carbon dioxide-obsessed Europe, although it will be exported to some other like-minded markets. Could one of them be North America? Seems not. A Mercedes source, pressured for an answer, says an “adequate alternative” is being considered for 2012 launch here in America. Best guess is it will use a version of the S400’s U.S.-spec powertrain.

Share this article in:

Share this article in:

We’ve Temporarily Removed Comments

As part of our ongoing efforts to make MotorTrend.com better, faster, and easier for you to use, we’ve temporarily removed comments as well as the ability to comment. We’re testing and reviewing options to possibly bring comments back. As always, thanks for reading MotorTrend.com.